class_docstr: Maps policy IDs to Policy objects.
  
  Thereby, keeps n policies in memory and - when capacity is reached -
  writes the least recently used to disk. This allows adding 100s of
  policies to a Algorithm for league-based setups w/o running out of memory.
docstr: Returns all valid values, even the stashed ones.
docstr_tok: ["Returns","all","valid","values",",","even","the","stashed","ones","."]
code: def values(self):
      """Returns all valid values, even the stashed ones."""
      self._lock.acquire()
      vs = [self[k] for k in self._valid_keys]
      self._lock.release()
  
      def gen():
          for value in vs:
              yield value
  
      return gen()
  
imports: from collections import deque
  import threading
  from typing import Dict, Set
  import logging
  import ray
  from ray.rllib.policy.policy import Policy
  from ray.rllib.utils.annotations import override
  from ray.rllib.utils.deprecation import deprecation_warning
  from ray.rllib.utils.framework import try_import_tf
  from ray.rllib.utils.threading import with_lock
  from ray.rllib.utils.typing import PolicyID
  from ray.util.annotations import PublicAPI
label_desc: Use image node_id 8 for calling the PolicyMap obj's underlying member method code with example usage: obj.values() and returns: gen